303 research outputs found
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Harvest Strategies for a Transboundary Resource: Georges Bank Haddock
The eastern Georges Bank haddock resource is shared and managed by the U.S. and Canada through a transboundary resource sharing agreement. This agreement includes an annual process for joint stock assessment, setting of a TAC, and harvest shares for each country. The resource sharing agreement provides a mechanism for establishing bilateral action by both countries, but covers only part of the total haddock stock on Georges Bank. The resource sharing agreement does not apply to non-Georges Bank haddock stocks in the U.S. and Canada. Haddock is an important source of income for U.S. and Canadian fishermen and is a commodity that is traded between the two countries. Thus, management decisions taken under the transboundary sharing agreement have implications for domestic markets in the U.S. and Canada and through trade links between the two countries. This paper explores the implications of pursuing different harvest strategies between the U.S. and Canada within an institutional setting that requires bilateral control over a portion of potential haddock supplies, yet provides opportunities to take unilateral action that could affect international trade and prices received by domestic fishermen in both countries
Renormalisation-induced phase transitions for unimodal maps
The thermodynamical formalism is studied for renormalisable maps of the
interval and the natural potential . Multiple and indeed
infinitely many phase transitions at positive can occur for some quadratic
maps. All unimodal quadratic maps with positive topological entropy exhibit a
phase transition in the negative spectrum.Comment: 14 pages, 2 figures. Revised following comments of referees. First
page is blan
Altered postural sway in patients suffering from non-specific neck pain and whiplash associated disorder - A systematic review of the literature
To assess differences in center of pressure (COP) measures in patients suffering from non-specific neck pain (NSNP) or whiplash-associated disorder (WAD) compared to healthy controls and any relationship between changes in postural sway and the presence of pain, its intensity, previous pain duration and the perceived level of disability. Summary of Background data: Over the past 20 years, the center of pressure (COP) has been commonly used as an index of postural stability in standing. While several studies investigated COP excursions in neck pain and WAD patients and compared these to healthy individuals, no comprehensive analysis of the reported differences in postural sway pattern exists. Search methods: Six online databases were systematically searched followed by a manual search of the retrieved papers. Selection Criteria: Papers comparing COP measures derived from bipedal static task conditions on a force plate of non-specific neck pain and WAD sufferers to those of healthy controls. Data collection and analysis: Two reviewers independently screened titles and abstracts for relevance. Screening for final inclusion, data extraction and quality assessment were carried out with a third reviewer to reconcile differences
Perception of Thermal Pain and the Thermal Grill Illusion Is Associated with Polymorphisms in the Serotonin Transporter Gene
AIM: The main aim of this study was to assess if the perception of thermal pain thresholds is associated with genetically inferred levels of expression of the 5-HT transporter (5-HTT). Additionally, the perception of the so-called thermal grill illusion (TGI) was assessed. Forty-four healthy individuals (27 females, 17 males) were selected a-priori based on their 5-HTTLPR/rs25531 ('tri-allelic 5-HTTLPR') genotype, with inferred high or low 5-HTT expression. Thresholds for heat- and cold-pain were determined along with the sensory and affective dimensions of the TGI. RESULTS: Thresholds to heat- and cold-pain correlated strongly (rho = -0.58, p<0.001). Individuals in the low 5-HTT-expressing group were significantly less sensitive to heat-pain (p = 0.02) and cold-pain (p = 0.03), compared to the high-expressing group. A significant gender-by-genotype interaction also emerged for cold-pain perception (p = 0.02); low 5-HTT-expressing females were less sensitive. The TGI was rated as significantly more unpleasant (affective-motivational dimension) than painful (sensory-discriminatory dimension), (p<0.001). Females in the low 5-HTT expressing group rated the TGI as significantly less unpleasant than high 5-HTT expressing females (p<0.05), with no such differences among men. CONCLUSION/SIGNIFICANCE: We demonstrate an association between inferred low 5-HTT expression and elevated thresholds to thermal pain in healthy non-depressed individuals. Despite the fact that reduced 5-HTT expression is a risk factor for chronic pain we found it to be related to hypoalgesia for threshold thermal pain. Low 5-HTT expression is, however, also a risk factor for depression where thermal insensitivity is often seen. Our results may thus contribute to a better understanding of the molecular underpinnings of such paradoxical hypoalgesia. The results point to a differential regulation of thermoafferent-information along the neuraxis on the basis of 5-HTT expression and gender. The TGI, suggested to rely on the central integration of thermoafferent-information, may prove a valuable tool in probing the affective-motivational dimension of these putative mechanisms
Biomimetic self-assembling copolymer-hydroxyapatite nanocomposites with the nanocrystal size controlled by citrate
Citrate binds strongly to the surface of calcium phosphate (apatite) nanocrystals in bone and is thought to prevent crystal thickening. In this work, citrate added as a regulatory element enabled molecular control of the size and stability of hydroxyapatite (HAp) nanocrystals in synthetic nanocomposites, fabricated with self-assembling block copolymer templates. The decrease of the HAp crystal size within the polymer matrix with increasing citrate concentration was documented by solid-state nuclear magnetic resonance (NMR) techniques and wide-angle X-ray diffraction (XRD), while the shapes of HAp nanocrystals were determined by transmission electron microscopy (TEM). Advanced NMR techniques were used to characterize the interfacial species and reveal enhanced interactions between mineral and organic matrix, concomitant with the size effects. The surface-to-volume ratios determined by NMR spectroscopy and long-range 31P{1H} dipolar dephasing show that 2, 10, and 40 mM citrate changes the thicknesses of the HAp crystals from 4 nm without citrate to 2.9, 2.8, and 2.3 nm, respectively. With citrate concentrations comparable to those in body fluids, HAp nanocrystals of sizes and morphologies similar to those in avian and bovine bones have been produced
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Challenges in Implementing Stock Assessment, Economic Fishery Analysis, and Risk Assessment for Sustainable Management Strategies of Data Poor Stocks
Under the IIFET 2018 Special Session “Tools for Stock Assessment, Economic Fishery Analysis, and Risk Assessment for Sustainable Management Strategies of Data Poor Stocks in Mixed, Small Scale and Indigenous Fisheries” a number of stakeholder presentations addressed the current status, challenges, needs and future perspectives for implementation of management and ecological / economic assessment of data poor fish stocks and fisheries in management advice. This covers methods, simulation models and management strategy evaluation (MSE) tools to conduct assessment and evaluate economic efficiency and risks in exploiting data poor stocks caught in mixed, small scale, and indigenous fisheries. Particular focus is on accessibility of models and their development to ensure widespread and open access availability, user-friendly model operation, and efficient widespread adoption and implementation of those by scientists, stakeholders, and managers. Additional focus is on the data requirements for those models. Finally, the aim of the session was to discuss the best possible way to link economic assessments, risk assessment and MSE with biological (ecological) assessment of stock status according to sustainable harvest levels in those data limited situations and systems to provide robust assessment and advice – and maybe even integrated ecological-economic advice
Evidence for Thalamic Involvement in the Thermal Grill Illusion: An fMRI Study
Perceptual illusions play an important role in untangling neural mechanisms underlying conscious phenomena. The thermal grill illusion (TGI) has been suggested as a promising model for exploring percepts involved in neuropathic pain, such as cold-allodynia (pain arising from contact with innocuous cold). The TGI is an unpleasant/painful sensation from touching juxtapositioned bars of cold and warm innocuous temperatures.To develop an MRI-compatible TGI-unit and explore the supraspinal correlates of the illusion, using fMRI, in a group of healthy volunteers.We constructed a TGI-thermode allowing the rapid presentation of warm(41°C), cold(18°C) and interleaved(41°C+18°C = TGI) temperatures in an fMRI-environment. Twenty volunteers were tested. The affective-motivational (“unpleasantness”) and sensory-disciminatory (“pain-intensity”) dimensions of each respective stimulus were rated. Functional images were analyzed at a corrected α-level <0.05.The TGI was rated as significantly more unpleasant and painful than stimulation with each of its constituent temperatures. Also, the TGI was rated as significantly more unpleasant than painful. Thermal stimulation versus neutral baseline revealed bilateral activations of the anterior insulae and fronto-parietal regions. Unlike its constituent temperatures the TGI displayed a strong activation of the right (contralateral) thalamus. Exploratory contrasts at a slightly more liberal threshold-level also revealed a TGI-activation of the right mid/anterior insula, correlating with ratings of unpleasantness(rho = 0.31).To the best of our knowledge, this is the first fMRI-study of the TGI. The activation of the anterior insula is consistent with this region's putative role in processing of homeostatically relevant feeling-states. Our results constitute the first neurophysiologic evidence of thalamic involvement in the TGI. Similar thalamic activity has previously been observed during evoked cold-allodynia in patients with central neuropathic pain. Our results further the understanding of the supraspinal correlates of the TGI-phenomenon and pave the way for future inquiries into if and how it may relate to neuropathic pain
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